Meso-mixing effects on demulsification in froth treatment: mechanisms and modeling

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All of Chemical Engineering can be broken into three basic steps: mixing, reaction, and separations. While reaction and separations have been extensively studied for centuries, the (technical) mixing literature only begins in the 1950's. For decades, we have taught students that processes are "well mixed" - but a technical and comprehensive definition of what we mean by well mixed only appeared in 2009 (Kukukova et al.) Mixing is frequently simple or ideal, but when it appears as a problem it is often elusive - appearing in one set of experiments and disappearing in other apparently similar work. There are two reasons for this: first, well defined mixing test cells have only recently been developed, and second, mixing is most frequently a competing rate process - it has strong interactions with other variables and cannot be considered in isolation. In this proposal, the initial stages of mixing additive into diluted bitumen froth are to be explored. In this process, if the additive is injected at a high concentration with poor mixing, clean up of the froth before processing is very difficult. If this additive is prediluted and mixed vigorously at the point of injection, the chemical use can be cut in half while achieving the same separation. This is a classical mesomixing problem, indicating that high local concentrations at the feed point are changing the chemical action taken by the demulsifier additive. New experimental tools allow us to look into the feed plume to see what is happening and determine the fate of the demulsifier. This is the first time in-situ measurements will be possible in real time.